TM 55-2210-224-34
3-24. POWER CONTACTOR (cont)
ADJUSTMENT (cont)
b.
Measure final pressure as follows:
(1)
Block the armature in the closed position.
(2)
Measure the pull required to just separate the contact tips.
(3)
Check for a pull of 12 to 16 lb (5.45 to 7.26 kg).
c.
If the pressure measurements are not correct, check for the following conditions:
(1) Low
initial
pressure
defective
contact
pressure spring, worn spring seat or washers,
or worn stop.
(2) Low final pressure defective pressure spring,
low wear allowance, or badly worn tips.
TEST
33.
Measure and adjust coil operating current as follows:
a.
Use a multimeter and measure resistance of coil.
Resistance shall be between 24.39 and 29.81
ohms. Replace defective coil.
b.
Connect power supply and ammeter to core.
c.
Apply current and increase slowly until contactor
picks up. Check that the contactor picks up without
hesitation, that is, in one quick motion including the
contact wipe. The current measured shall be 0.638
to 0.775 amperes.
d.
Adjust calibrating screw until proper valve of
current is indicated.
34.
Manually operate interlock contacts. Use a multimeter and check resistance of contacts for infinity while open and
continuity while closed.
3-99
